This invention relates generally to sleeve-type low pressure responsive APR tester valves and more particularly, but not by way of limitation, to a sleeve-type low pressure responsive APR tester valve capable of controlling its operation regardless of temperature effects brought about by relatively cold fluids pumped through the tester valve.
The present invention is particularly useful in testing of offshore wells where it is desirable to conduct testing operations and well stimulation operations utilizing the testing string tools with a minimum of testing string manipulation, and preferably with the blowout preventors closed during most operations.
It is known in the art that tester valves and sampler valves for use in oil and gas wells may be operated by applying pressure increases to the fluid in the annulus between the wellbore and the testing string disposed in the well. It is also known that such valves can include either ball-type or sleeve-type valves. In the ball-type valve a spherical member is rotatable between closed and opened positions, whereas in the sleeve-type valve two telescopic members are relatively slidable between closed and opened positions.
It is also known that low pressure responsive APR tester valves adapted for metering flows of the fluid whereby proper operation is achieved regardless of temperature effects are also known. Such a low pressure responsive APR tester valve, which utilizes a ball-type valve, is disclosed in U.S. Pat. No. 4,429,748 to Beck.
It has become desirable to have a tester valve of the general type described in U.S. Pat. No. 4,429,748, but with a sleeve-type valve with a simpler construction and operation. In such a new type of tester valve, it is also desirable to have the capability of using a selectable one of a plurality of chokes for properly controlling the flow through the valve to reduce washing effects which abrade or wear the surfaces of the valve and valve case. This choke may also aid in obtaining reservoir data for quantitative interpretation. A further significant need is to provide a sleeve-type tester valve that can be pressure tested to pressure levels in excess of those which can be performed with a ball-type tester valve. Furthermore, to permit the economical use of both ball and sleeve types where needed, it would be preferable to construct such a sleeve-type valve so that it can be readily connectible to the prior art low pressure responsive APR tester valves directly in place of the presently known ball valve section thereof.